Oral cavity & oropharynx

Soft tissue tumors & proliferations

Irritation fibroma

Editorial Board Member: Kelly Magliocca, D.D.S., M.P.H.
Editor-in-Chief: Debra L. Zynger, M.D.
Molly Housley Smith, D.M.D.

Last author update: 26 October 2020
Last staff update: 26 October 2020

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PubMed Search: Irritation fibroma oral cavity

Molly Housley Smith, D.M.D.
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Cite this page: Smith MH. Irritation fibroma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/oralcavityirritationfibroma.html. Accessed June 2nd, 2023.
Definition / general
  • Fibrous nodule of oral cavity, often considered a reactive hyperplasia to trauma or local sources of irritation
Essential features
  • Common reactive fibrous hyperplasia of oral cavity
  • Typically affects buccal mucosa along the line of occlusion / bite line
  • Conservative surgical excision is recommended and recurrences are rare
  • Irritation fibroma
  • Oral fibroma
  • Traumatic fibroma
  • Focal fibrous hyperplasia
ICD coding
  • Reactive fibrous tissue:
    • ICD-10: K13.79 - Other lesions of oral mucosa
  • True benign fibrous tumor with continuous growth:
    • ICD-10: D10.0 - Benign neoplasm of lip
  • Thought to be induced by recurrent local irritants of the oral cavity, which may include bite trauma, denture irritation, food impaction, poor oral hygiene, broken teeth or overhanging dental restorations (Iran J Otorhinolaryngol 2015;27:137)
Clinical features
  • Definitive diagnosis is made upon histopathological review, although irritation fibromas may be highly suspected based on clinical features (Braz J Otorhinolaryngol 2019;85:399)
Prognostic factors
  • Excellent prognosis with infrequent recurrence after conservative surgical excision
Case reports
Clinical images

Contributed by Brandon Stapleton, D.M.D., Molly Housley Smith, D.M.D. and Jimmy Vellis, D.D.S., M.S.

Fibroma of buccal mucosa

Fibroma of the tongue

Ulcerated irritation fibroma

Gross description
  • Tan or gray nodule of soft tissue with white cut surface
  • Surface ulceration or thickened keratin surface may be present
Gross images

Contributed by Molly Housley Smith, D.M.D.

Tan to gray nodule

Cut surface

Microscopic (histologic) description
  • Nonencapsulated nodular mass
  • Mass composed of fibrous connective tissue with collagen bundles interspersed with fibroblasts, blood vessels and scattered chronic inflammatory cells
  • Overlying surface of squamous epithelium (J Oral Maxillofac Pathol 2015;19:330)
Microscopic (histologic) images

Contributed by Molly Housley Smith, D.M.D.

Nodular mass

Hyperkeratotic surface

Scattered chronic inflammatory cells

Positive stains
Negative stains
Sample pathology report
  • Right buccal mucosa, excisional biopsy:
    • Focal fibrous hyperplasia (irritation fibroma)
Differential diagnosis
  • Clinical:
    • Nodules of neural, muscular, lipomatous, vascular or salivary gland origins, as well as fibrous proliferations associated with embedded foreign material (e.g. dermal fillers); proper diagnosis is made upon histopathological review
    • Multiple fibrous nodules may be associated with various syndromes (e.g. Cowden syndrome) (Cancers (Basel) 2019;11:844)
    • Multiple endocrine neoplasia, type 2B (MEN 2B):
      • Bilateral flesh colored nodules in the oral commissure regions or multiple nodules of the tip of the tongue are highly suggestive of MEN 2B (Head Neck Pathol 2017;11:364)
      • Biopsy of the nodules reveals a diagnosis of mucosal neuroma
  • Histopathological:
    • Giant cell fibroma (which is of little consequence):
Board review style question #1

A 56 year old man presents with a chief complaint of a bump inside the oral cavity. On clinical exam, a pink, smooth surfaced nodule is noted along the patient’s bite line. He states that the mass interferes with chewing and speaking. The microscopic appearance is pictured. What is the diagnosis?

  1. Irritation fibroma
  2. Lipoma
  3. Neurofibroma
  4. Pleomorphic adenoma
Board review style answer #1
A. Irritation fibroma. Although all of the entities listed fall under the clinical differential diagnosis list, the histology demonstrates a nodular mass of fibrous connective tissue with scattered fibroblasts, blood vessels and chronic inflammatory cells, which rules out all of the listed entities except irritation fibroma.

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Reference: Irritation fibroma
Board review style question #2

A 61 year old woman presents with a solitary nodular mass of the oral buccal mucosa that has been present over 5 years with minimal change. Histopathological review of the mass reveals a fibrous mass containing collagen bundles interspersed with fibroblasts and blood vessels. Which of the following is true regarding this pathological entity?

  1. Lesional tissue is positive upon immunohistochemistry with S100
  2. The patient should be evaluated for multiple endocrine neoplasia, type 2B
  3. This entity represents most likely represents a reactive hyperplasia rather than a true tumor
  4. Without surgical excision, this mass will continue to grow to enormous size
Board review style answer #2
C. This entity represents most likely represents a reactive hyperplasia rather than a true tumor. The pathological entity described is an irritation fibroma. Irritation fibromas are the most common oral reactive lesion. While irritation fibromas would be positive upon immunohistochemical staining with vimentin, they are negative with S100, SMA, CD34 and other soft tissue markers. MEN 2B should be considered in a patient with bilateral flesh colored nodules in the commissures of the mouth or multiple nodules of the tip of the tongue, although the biopsy results would reveal a mucosal neuroma rather than purely fibrous connective tissue. Because irritation fibrous are not considered true tumors, they often do not grow with unlimited potential. They most frequently measure 1 - 2 cm in diameter and may increase or decrease in size depending on local irritating factors.

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Reference: Irritation fibroma
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